Blocked linear secret sharing scheme for scalable attribute based encryption in manageable cloud storage system

Cloud provides outsourced storage services in a cost-effective manner. A key challenge of cloud storage is the security and privacy of outsourced data. A security mechanism known as attribute-based encryption (ABE) represents the state-of-the-art in providing fine-grained access control for cloud storage. The managing of access policy is a critical issue of ABE. Policy managing may incur substantial computation and communication overhead in the ABE scheme with unscalable access policy. In this work, we firstly propose a form of scalable access policy named blocked linear secret sharing scheme (BLSSS). The scalability of BLSSS provides efficient policy managing interface for ABE scheme. Then, we propose a scalable ciphertext-policy attribute-based encryption (SCP-ABE) scheme which uses BLSSS as access policy. Significantly, the proposed SCP-ABE is low-cost in computation and communication during policy managing. Furthermore, sufficient simulation experiments demonstrate that SCP-ABE outperforms most existing ABE schemes in terms of policy managing.